1. Field
The present invention relates to hydrogen peroxide complexes as well as anaerobic curable compositions employing these complexes.
2. Brief Description of Related Technology
Anaerobic adhesive compositions are well known for their ability to remain in a liquid, unpolymerized state in the presence of oxygen and to cure to a solid state upon the exclusion of oxygen. Early work on anaerobic adhesive compositions concentrated on developing a cure system which improved the speed and/or bond strength of the adhesive composition. Various cure systems for anaerobic adhesive compositions have been developed to primarily focus on efficiently performing the redox reaction, which is the basis for anaerobic chemistry.
Anaerobic compositions generally contain (meth)acrylic functional monomers, an organic hydroperoxy or perester initiator, accelerators such as saccharin and/or dimethyl-p-toluidene, stabilizers such as hydroquinone or other phenolic stabilizers and metal chelators such as sodium EDTA. Those persons of ordinary skill in the art acknowledge that peroxides serve as a free radical generating source which initiate free radical curing of the polymerizable anaerobic adhesive monomer compositions. Illustrative of such initiators are the diacyl peroxides such as benzoyl peroxide; dialkyl peroxides such as di-tert-butyl peroxide; ketone peroxides such as methylethyl ketone peroxide; and peresters which readily hydrolyze, e.g., tert-butyl peracetate, tert-butyl perbenzoate and di-tert-butyl diperphithalate.
A particularly useful class of peroxy initiators is the organic hydroperoxides such as cumene hydroperoxide (“CHP”), methylethylketone hydroperoxide, tert-butyl hydroperoxide (“TBH”) and methylethyl ketone hydroperoxide. Of these, cumene hydroperoxide is especially popular. However, the peroxy initiators currently used in the art suffer from several deficiencies. For instance, alkyl hydroperoxides, such as cumene hydroperoxide, have a distinctive, objectionable odor. In addition, there are concerns about the toxicity of cumene hydroperoxide.
Notwithstanding the state of the art, there is an on-going desire to find alternative technologies for peroxy initiators and anaerobic compositions to differentiate existing products, overcome deficiencies in the art and provide supply assurances in the event of shortages or cessation of supply of raw materials. Accordingly, it would be desirable to identify new materials that function as a peroxy initiator and can be used in anaerobically curable compositions.